Project Summary Prostate cancer (CaP) is the commonest internal malignancy in U.S. men. More than 180,000 new cases and 26,000 deaths are expected during 2016, making it the 2nd most common cause of cancer death in men. Focal therapy, a new alternative for men with intermediate risk CaP ? a group estimated by NCI to comprise as many as 60,000 new cases every year ? has become a subject of keen interest. Of the various energies for focal therapy, laser ablation (FLA) is compelling because of its precision and because it offers the potential of an outpatient treatment without need for general anesthesia or an operating room. Ordinarily performed under direct MRI guidance, FLA is capable of producing a well-defined zone of coagulation necrosis via hyperthermia within the prostate without damage to adjacent tissue and without causing incontinence or erectile dysfunction. The linchpin of CaP focal therapy is targeted biopsy, a procedure that we started in 2009 and developed under a previous Academic-Industrial R01 grant. In targeted biopsy, multi-parametric MRI is used for imaging and the Artemis device is used for fusing stored MR images with real-time ultrasound. Biopsy in the clinic can then be directed at suspicious regions seen on MRI. Approximately 2500 such procedures have been performed at UCLA, among the largest experience extant, and thus our team has gained considerable expertise placing biopsy needles into localized prostate cancers. Using knowledge from the biopsy program, we performed FLA on 8 men in-bore, i.e., inside an MRI tube, using direct MRI guidance for localization and MR thermometry for monitoring. The in-bore treatments proved safe and feasible, but lengthy, expensive, and resource-intensive, lacking the potential for widespread adoption. Therefore, we brought the procedure into the clinic, using MR/US fusion for guidance and direct thermal probes for temperature monitoring. The clinic procedures (N=10), performed under an IDE from FDA, yielded results like the in-bore procedures, but were much simpler, quicker, and potentially less expensive. We propose to build upon a substantial preliminary experience to create and test a technology that would allow widespread adoption of FLA for CaP. Translation of the idea into clinical practice depends upon (a) MRI/US fusion for guidance, with which we already have expertise, (b) thermal probes for intra-prostatic temperature monitoring, to be fabricated by partner LumaSense, and (c) a novel ultrasound probe to allow visualization of both laser and thermal probe, to be fabricated by partner MDMedtech. While not official partners, Medtronic has endorsed this project by donating the Visualase system and Hitachi by donating the ultrasound machine. Work would begin with creation and testing of each system component, followed by a multi-institution validation study (UCLA/Stanford/Cornell) in men with intermediate-risk CaP, employing before and follow-up targeted biopsy to prove efficacy. Successful completion of the project would lead to a safe, effective, economical system for clinic-based treatment of prostate cancer applicable to tens of thousands of men every year.